They are so alike, I can't tell which is which.
The twins are so alike I can't tell which is which.
Who says which is which
Mary and Susan are twins and I can't tell which is which.
Can you tell which is which?
The kittens look exactly alike—how can you tell which is which ?
The twins are so much alike that I never knew which is which.
Now which is which?
Tag the bottles now or we' ll forget which is which.
In the absence of good scientific trials, it is impossible to be certain which is which.
